Preparing metal for drawing operations



Patented Dec. 28, 1943 PREPARING METAL FOR DRAJVING OPERATIONS William E. Leonard, Worcester, lilass assignor to The American Steel and Wire Company of New Jersey, a corporation of New Jersey No Drawing. Application August 4, 1940, Serial No. 351,432

3 Claims.

This invention pertains to treatment of metal .and, more particularly, elongated ferrous stock,

drawing industry, to pickle rods to remove scale vi or rust therefrom, to wash the rods in water and then to immerse them in a lime solution so as to obtain a coating of the latter, after which the rods are sent to an oven or baker so as to drive off the moisture and to leave a dry lime deposit thereupon. I

These conventional practices have been sub-- ject to criticism, first, in that acid residues remaining from the cleaning operation found their way into the lime tank, causing calcium sulphides and chlorides to form on the surface of the stock, which chemicals are hard and exceedingly deleterious to the dies through which the stock must subsequently be drawn, and secondly, the practice of baking the lime upon the rod or other ferrous stock required the outlay of ovens or bakers of considerable size, the initial cost of which was not only considerable, but the maintenance and operation thereof, both as to fuel and labor, likewise represented a considerable cost item.-

The cleaning, liming and baking of rods has usually been effected by the batch process, that is, the coils of rod were handled as such and immersed successively in several tanks and passed through the bakers on buggies. time inthe baker was a matter of hours, usually running up to twenty-four to thirty-six hours, depending upon the production requirements. It was thought that the time in the baker was necessary, first, thoroughly to dry the lime upon the surface of the rod, and, secondly, to drive off if any residual acid that might still be present, or hydrogen that might be occluded in the Surface of the metal as the result of such acids.

It is the primary object of the present inventlon.to eliminate the formation of hard chemical compounds deleterious to die life in the drawing of limed rods and wire and to eliminate the baking practice both as to the time and handling of the material itself, and the large and expensive equipment required for this purpose.

Other objects and advantages will become apparent hereinafter when the following specification and claims are read and the description thereof is developed.

Rods, or other elongated metal stock, thoroughly cleaned in accordance with any suitable method, are first washed and are then immersed in a strong caustic or-alkaline solution, that The course of which is known to the trade as 24 Oakite in' solution with water having been found suitable for the purpose. The composition of said No. 24 Oakite is as follows: moisture, 16.6%; sodium resinate, 10.9%; sodium hydroxide, 30.8%; sodium carbonate, 29.8%; and sodium silicate, 11.9%. The metal stock remains in this caustic solution for fifteen minutes or more, which is maintained at a temperature of 250280 F. This serves two purposes, first, thoroughly to neutraliae any acid remaining on the Wire, and secondly, to preheat the wire as hot as possible up to the boiling point of the caustic solution.

The rods are then removed and immersed in a hotlime bath which may run from 3-12% more or less lime, and which is maintained at 212 F.

The material is then moved fr m the lime bath and is left suspended in air at sual room temperatures, with or without the aid of a fan blowing thereupon, or is exposed to a hot atmosphere for a few seconds so as thoroughly to dry the coils of wire, and particularly the bottom portions of .the' convolutions thereof, down to wl'zich moisture of-the bundle necessarily gravitates.

The residual heat of the wire plus the fan and/or hot air currents cause the material to dry quite rapidly as it is suspended from a handling crane so that the lime is left dry and soft without the need of any baker or other lengthy practice and elaborate equipment.

The foregoing practice has not only shown a remarkable economy of labor, time, and equipment, but has likewise been the means of improving die-life considerably by the elimination of sulphides, sulphates, chlorides, etc., on the surface of the metal stock, heretofore attributable to the presence of acid upon the stock surface when immersed in the lime tank.

While I have described one pecific embodiment of my invention, it will be understood that'I do not Wish to be limited exactly thereto, since various modifications may be made Without departing from the scope of my invention, as defined by the following claims.

I claim: I

1. The method of processing metal wire or rod stock for reduction in gauge, which consists in cleaning said stock in an acid solution, immersing said stockin an alkali solution having the composition of No. 24 Oakite to neutralize residual acid on the stock, immersing said stock in a lime suspension so as to acquire a non-reacting coating of the suspensoid thereon, and subjecting the applied under average room conditions, and subsequently subjecting the stock to a wire-drawing operation to reduce the gauge thereof.

3. The invention according to claim 2, in which the stock is in coiled form and during the drying of lime thereon, subjecting the bottom regions of the coils to a temperature materially above room temperature to assist in dissipating the excess moisture accumulated at such region.

W. E. LEONARD. 

